1. Field of the Invention
The invention relates to a method and an apparatus for setting up data and communication links between vehicles.
2. Description of the Related Art
In digital communication systems, i.e. in communication systems in which the signal to be transferred is digitized and is transferred from the sender to the receiver in digital form, for example in mobile radio systems, optimum and efficient management of the entire system requires the number of bits for transferring a particular piece of information to be kept as small as possible. Such bit reduction is usually achieved by a particular kind of source encoding. In existing information systems, information about local events is brought together at central locations (servers). From there, the information is transmitted to the road users by radio systems by means of a broadcast. Such systems, such as broadcast radio based on analog transfer or digital transfer (DAB, Digital Audio Broadcasting) or, in future, based on DVB-T/S (Digital Video Broadcasting-Terrestrial/Satellite), are pure broadcast systems without functions for bidirectional transfer.
Alternatively, this information can be provided in mobile radio networks, e.g. based on the GSM, GPRS or UMTS standard (GSM: Global vehicle telematics apparatus for mobile communication; UMTS: Universal Mobile Telecommunication System), by means of supplementary services, such as a short message service (SMS), local radio data networks (W-LAN: Wireless Local Area Network) or information services. This allows the desired information to be retrieved in targeted fashion when required. Before it is possible to access the information, however, it needs to be transferred from the location of its occurrence to the central unit (server). Only from there is this information passed to the mobile end subscriber following connection setup. Before this information is available, the transfer to the server and from there to the end subscriber therefore takes time, which means that the contemporariness of the message suffers as a result and in many cases is worthless, e.g. if the road user is already at or close to the end of the tailback. Radio systems which exist at present therefore cannot be used to transfer time-critical messages.
DE 102004056724A1 discloses a method for transferring data in a communication network with direct vehicle-vehicle communication, wherein a receiving vehicle receives communication signals from a sending vehicle. The receiving vehicle ascertains or updates a piece of trust information, the trust information making it possible to establish whether data sent by the sending vehicle are trustworthy and/or how trustworthy data sent by the sending vehicle are. The trust information is ascertained using a user certificate which has been issued by a trustworthy institution and/or which has been produced by a device in the communication network using information from a first certificate issued by the trustworthy institution.